1. Field of the Invention
This invention relates to an object lens device, more particularly to an object lens device that permits adjustments to relative distances among components thereof.
2. Description of the Related Art
As shown in FIG. 1, a conventional object lens device 1 can be mounted onto a conventional optical device, such as an optical sight 2. The optical sight 2 includes a first end part 21 that has the conventional object lens device 1 connected thereto, a second end part 23 that is connected to an eyepiece unit 22, and an inverting lens unit (not shown in the figure) disposed between the object lens device 1 and the eyepiece unit 22.
As shown in FIG. 2 and FIG. 3, the object lens device 1 includes an outer barrel 11, a rotary component 12, an object lens unit 13, a decorative unit 14, and a limiting unit 15.
The rotary component 12 is threadedly connected to the outer barrel 11, and can translate along an optical axis (X) when rotated.
The object lens unit 13 is disposed in the outer barrel 11 and is capable of limited translation along the optical axis (X). The object lens unit 13 includes a lens barrel 131 that surrounds the optical axis (X), and two object lenses 132 that are mounted in the lens barrel 131. The lens barrel 131 has first and second ends 133, 134 that are opposite to each other along the optical axis (X).
The decorative unit 14 includes a decorative ring 141 that surrounds the optical axis (X), and a colored ring 142. A part of the decorative ring 141 is threadedly connected to an inner surface 121 of the rotary component 12. The colored ring 142 has opposite ends 143, 144 along the optical axis (X) that abut respectively against the decorative ring 141 and the rotary component 12. The colored ring 142 can prevent excessive screwing between the decorative ring 141 and the rotary component 12. The colored ring 142 also enhances the aesthetic appeal of the conventional object lens device 1 by having a different color from that of the decorative ring 141 and the rotary component 12.
The limiting unit 15 includes a press ring 151 that surrounds the optical axis (X), and a biasing member 152. The press ring 151 is threadedly connected to the inner surface 121 of the rotary component 12, and abuts against the first end 133 of the lens barrel 131. The biasing member 152 is disposed in the outer barrel 12, and abuts against the second end 134 of the lens barrel 131 so that the object lens unit 13 is biased to constantly abut against the press ring 151.
Referring to FIG. 1 and FIG. 3, when a user rotates the rotary component 12, the rotary component 12, together with the press ring 151 and the decorative ring 142, translate along the optical axis (X). Meanwhile, the biasing member 152 reacts to the amount of movement made by the press ring 151 in terms of elastic forces and causes the object lens unit 13 to translate along the optical axis (X) inside the outer barrel 11, thereby performing focusing adjustments. Although the conventional object lens device 1 is capable of performing focusing adjustments, it has the following shortcomings:
1. In order to increase focusing accuracy, before conventional optical devices, such as the optical sight 2, are delivered from factories, the distance of the object lens unit 13 relative to the eyepiece unit 22 is adjusted to offset parallax by adjusting the depth of the threaded interconnection between the press ring 151 and the rotary component 12. However, the object lens unit 13 usually has a specified total length for application to different optical devices. Therefore, when the total length of the object lens unit 13 is kept constant, while the press ring 151 and the decorative ring 141 are both threadedly connected to the inner surface 121 of the rotary component 12, the press ring 151 is spatially limited by other components of the conventional object lens device 1, thereby resulting in a small distance (L1) for offsetting parallax. The distance (L1) is usually insufficient for offsetting parallax, and thereby affects the focusing accuracy of conventional optical devices.
2. The decorative ring 142 is required to be removed in order to adjust the depth of the threaded interconnection between the press ring 151 and the rotary component 12. Therefore, it is very inconvenient and time-consuming to perform adjustments to offset parallax.